1. Technical Field of Invention
The present invention relates to novel cosmetic compositions for topical application, for the photoprotection of the skin and/or hair against ultraviolet radiation (such compositions hereinafter simply designated "antisun," "sunscreen" or "photoprotective" compositions) and to the use of the same for the cosmetic applications indicated above.
This invention more especially relates to the aforesaid sunscreen/cosmetic compositions comprising, formulated into a cosmetically acceptable vehicle, diluent or carrier therefor, binary combination of (a) at least one bisresorcinyltriazine compound, as a first screening agent, and (b) at least one compound containing at least two benzoazolyl groups and/or at least one compound containing at least one benzodiazolyl group, as a second screening agent, the said first and second screening agents being present in the subject compositions in proportions eliciting a synergistic effect with regard to the protection factors conferred.
2. Description of the Prior Art
It is known to this art that light radiation of wavelengths of from 280 nm to 400 nm promotes tanning of the human epidermis and that irradiation with wavelengths of from 280 to 320 nm, i.e., UV-B radiation, cause erythemas and skin burns which may be harmful to the development of natural tanning; this UV-B radiation must therefore be screened from the skin.
It is also known to this art that UV-A radiation, with wavelengths of from 320 to 400 nm, which causes tanning of the skin, can also adversely affect it, in particular in the case of sensitive skin or of skin continually exposed to solar radiation. UV-A rays cause, in particular, a loss in the elasticity of the skin and the appearance of wrinkles, resulting in premature aging. Such irradiation promotes the triggering of the erythemal reaction or accentuates this reaction in certain individuals and can even be the cause of phototoxic or photoallergic reactions. It is therefore desirable to also screen out UV-A radiation.
A wide variety of cosmetic compositions for the photoprotection (UV-A and/or UV-B) of the skin are known to this art.
These photoprotective/sunscreen compositions are typically emulsions of oil-in-water type (namely, a cosmetically acceptable vehicle, diluent or carrier comprising a continuous aqueous dispersing phase and a non-continuous oily dispersed phase) which contains, in various concentrations, one or more conventional lipophilic and/or hydrophilic organic screening agents capable of selectively absorbing harmful UV radiation. These screening agents (and their amounts) are selected according to the desired protection factor (the protection factor (PF) being expressed mathematically by the ratio of the irradiation time required to attain the erythemogenic threshold with the UV screening agent to the time required to attain the erythemogenic threshold without UV screening agent).